How Far Do Teachers Go Beyond Mathematics Textbooks to Teach Reasoning and Proof in Eighth‐Grade Geometry Classrooms?

This study examined the relationship between reasoning and proof (RP) opportunities in eighth‐grade mathematics textbooks and classroom practices in China. Using an adapted framework that connects mathematical tasks in the written and implemented curriculum through the lens of teachers' decision‐making, the study analysed two textbook editions and 24 videotaped geometry lessons. The findings revealed a strong congruence between RP opportunities in textbooks and classroom implementation, with teachers primarily relying on textbooks for RP instruction, particularly focusing on demonstrations and conjecture‐making. However, limited opportunities for evaluating arguments were observed, and other types of RP were absent. These results underscore the need for a balanced approach in RP teaching practices to adequately support students' comprehensive development in RP. The adapted framework can serve as a valuable tool for future research on both written and implemented curricula across various mathematical content and grade levels. Additionally, the study highlights the importance of textbook development and teacher professional development in enhancing the quality and diversity of RP opportunities available to students.